Again, Robin wasn't challenging Maharishi's teaching but rather the organization that had been created to promote them. Robin did "remain a slave" to Maharishi and his teachings even many years after he'd been thrown out of Fairfield.
I left before the Robin Carlson period, but I imagine he created quite a challenge to the existing structure. So, I am not surprised that the powers that be felt alarmed. Yes, these pesky people that stay on the programme, get enlightened and then start doing what Marshy said they should do. What can we do with them? Why, ban them obviously, can't have people with different opinions wandering about and demonstrating that acting in accord with "nature" doesn't mean that you stay a slave to the reesh and his own teachings.